United States
Environmental Protection
Agency
Transportation and Air Quality
Transportation and Regional
Programs Division
EPA420-F-00-037
March 2002
www.epa.gov
SUCCESS STOfty
Georgetown University
in Washington, DC, has
successfully developed a fuel
cell that uses methanol—a
fuel derived from renewable
sources and readily available
at a reasonable price. Grant-
ed money in 1991 from the
U.S. Federal Transit Admin-
istration, Georgetown has
actively researched using
fuel cells in transit buses.
The university has proposed
building eight fuel cell-pow-
ered transit buses for
research and testing.
Through this program,
Georgetown has learned
valuable information about
fuel cell technology's perfor-
mance and promise. The
university's research will play
an important role in the
future commercialization of
fuel cell technology for vehi-
cles.
For more information,
contact James Larkins,
Georgetown's program
manager, at (202) 687-
7361.
Clean
Fuels:
Fuel Cells
One in a series of fact sheets
From midsize passenger vehicles to large transit bus fleets, fuel
cells offer a promising new source of clean power for electric vehi-
cles. This innovative technology uses chemical energy rather than
combustion to generate electric power, resulting in far fewer emissions. In
addition, fuel cell vehicles can utilize renewable fuel and are expected to pro-
vide a wider driving range than today's battery-powered electric vehicles. At
least seven types of fuel cells are currently being researched (see box).
Fuel cells generate power through an elec-
trochemical process, much like a battery.
They convert chemical energy to electrical
energy by combining hydrogen from fuel
with oxygen from the air. Hydrogen fuel
can be supplied in two ways—either
directly as pure hydrogen gas or through a
"fuel reformer" that converts hydrocarbon
fuels such as methanol, natural gas, or
gasoline into hydrogen-rich gas.
AVAILABILITY
Three major U.S. manufacturers and sev-
eral European and Japanese manufacturers
are actively researching fuel cell trans-
portation technologies and testing proto-
type passenger vehicles. Several North
American cities are also testing fuel cell-
powered transit buses. There are no fuel
cell vehicles currently available for sale in
the United States, but one major U.S.
automaker has announced plans to make
40,000 fuel cell vehicles available for pur-
chase by the general public by 2004. At
least four other manufacturers also plan to
market fuel cell vehicles that year.
Providing fuel to power these vehicles
presents several challenges. Large invest-
ments are required to establish hydrogen
production facilities and a convenient
hydrogen distribution system to serve the
general public. As an alternative, manufac-
turers are working to improve fuel reform-
ers to allow fuel cell vehicles to use
conventional fuels, which would
encourage consumer acceptance of this
technology.
EMISSIONS
CHARACTERIST
|CS*
* R
Actual emissions will vary wi
engine design.
• Fuel cell vehicles operating on
hydrogen or methanol can achieve
zero emission vehicle levels.
• Fuel cells operating with a fuel
reformer emit water vapor, carbon
dioxide, and hydrocarbon emissions.
* Estimates based on fuel cell's inherently
"cleaner" properties.
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AFFORDABILITY
There is no data currently available
on fuel cell vehicle costs because the
vehicles are not yet commercially
available. Vehicle costs are expected
to vary depending on the fuel cell
technology used and the scale of
vehicle production. Fuel prices also
will vary. Though hydrogen derived
from natural gas is more expensive
than conventional fuels, vehicles
fueled by hydrogen achieve greater
fuel economy. Keys to making these
vehicles cost-competitive include
providing low-cost, high-volume
manufacturing processes, as well as
lightweight, compact, and affordable
hydrogen storage systems.
PERFORMANCE
Because the technology is still under
development, fuel cell vehicles' per-
formance has not been well-studied
or documented. Based on available
research, fuel cell vehicles are expect-
ed to offer an extremely quiet ride
with little vibration. Compared with
conventional vehicles, fuel cell vehi-
cles are also expected to provide
improved fuel economy, increased
engine efficiency, lower smog-
forming emissions, and reduced
greenhouse gas emissions.
SAFETY
Safety issues vary depending on the
specific fuel source used. Although
most fuel cells, fuel reformers, and
fuel storage systems are not heavier
than conventional systems, some may
be. For such systems, the added
weight can make stopping the vehicle
more difficult. The onboard fuel
reformers also present unique safety
concerns—some reformers can gen-
erate internal temperatures up to
1,000°C and produce steam or steam
fuel mixtures at very high pressures.
For More Information
EPA Alternative Fuels Web Site
www.epa.gov/otaq/
consumer/fuels/altfuels/
altfuels.htm
Fuel Cell Institute
P.O. Box 65481
Washington, DC 20035
Phone:301681-3532
Fax:301681-4896
Alternative Fuels Data Center
Web site: www.afdc.nrel.gov
National Alternative Fuels
Hotline
Phone: 800 423-1 DOE
Types of Fuel Cells
All fuel cells contain two electrodes—one positively and one negatively charged—with a substance that conducts
electricity (electrolyte) sandwiched between them. Fuel cells can achieve 40 to 70 percent efficiency, which is sub-
stantially greater than the 30 percent efficiency of the most efficient internal combustion engines. The following
are different types of fuel cells:
• Phosphoric Acid—The most commercially developed fuel cell, generates electricity at more than 40 percent
efficiency.
• Proton Exchange Membrane—Considered the leading fuel cell type for passenger car applications, operates at
relatively low temperatures and a high power density.
• Molten Carbonate—Promises high fuel-to-electricity efficiencies and the ability to utilize coal-based fuels.
• Solid Oxide—Can reach 60 percent power-generating efficiencies and be employed for large, high-powered
applications such as industrial generating stations.
• Alkaline—Used extensively by the space program, can achieve 70 percent power-generating efficiencies, but is
considered too costly for transportation applications.
• Direct Methanol—Expected efficiencies of 40 percent with low operating temperatures; able to use hydrogen
from methanol without a reformer.
• Regenerative—Currently being researched by NASA; closed loop form of power generation that uses solar
energy to separate water into hydrogen and oxygen.
Printed on paper that contains at least 30 percent postconsumer fiber.
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